linux-kernel - [PATCH V2 06/12] OPP: Don't take OPP table's kref for static OPPs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 19 Sep 2018 15:20:25 -0700
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>,
        Rafael Wysocki <rjw@...ysocki.net>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Niklas Cassel <niklas.cassel@...aro.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH V2 06/12] OPP: Don't take OPP table's kref for static OPPs

The reference count is only required to be incremented for every call
that may lead to adding the OPP table. For static OPPs the same should
be done from the parent routine which adds all static OPPs together and
so only one refcount for all static OPPs.

Update code to reflect that.

The refcount is incremented every time a dynamic OPP is created (as that
can lead to creating the OPP table) and the same is dropped when the OPP
is removed.

Tested-by: Niklas Cassel <niklas.cassel@...aro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 drivers/opp/core.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 332748adc262..2a6976265580 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -919,7 +919,6 @@ static void _opp_kref_release(struct kref *kref)
 	kfree(opp);
 
 	mutex_unlock(&opp_table->lock);
-	dev_pm_opp_put_opp_table(opp_table);
 }
 
 void dev_pm_opp_get(struct dev_pm_opp *opp)
@@ -963,11 +962,15 @@ void dev_pm_opp_remove(struct device *dev, unsigned long freq)
 
 	if (found) {
 		dev_pm_opp_put(opp);
+
+		/* Drop the reference taken by dev_pm_opp_add() */
+		dev_pm_opp_put_opp_table(opp_table);
 	} else {
 		dev_warn(dev, "%s: Couldn't find OPP with freq: %lu\n",
 			 __func__, freq);
 	}
 
+	/* Drop the reference taken by _find_opp_table() */
 	dev_pm_opp_put_opp_table(opp_table);
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_remove);
@@ -1085,9 +1088,6 @@ int _opp_add(struct device *dev, struct dev_pm_opp *new_opp,
 	new_opp->opp_table = opp_table;
 	kref_init(&new_opp->kref);
 
-	/* Get a reference to the OPP table */
-	_get_opp_table_kref(opp_table);
-
 	ret = opp_debug_create_one(new_opp, opp_table);
 	if (ret)
 		dev_err(dev, "%s: Failed to register opp to debugfs (%d)\n",
@@ -1566,8 +1566,9 @@ int dev_pm_opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
 		return -ENOMEM;
 
 	ret = _opp_add_v1(opp_table, dev, freq, u_volt, true);
+	if (ret)
+		dev_pm_opp_put_opp_table(opp_table);
 
-	dev_pm_opp_put_opp_table(opp_table);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_add);
-- 
2.14.1